SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '852a7e9651180dc9b79020b1f8f3a47dba1eaac69e3de17084476d3d46a2fa6f' 
  AND token = 'l+U0yVvKvioXDub4JqTSWQsjbW9CxaxAN4MLYMjZRGM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}